This application claims the priority of German application 199 18 257.4, filed Apr. 22, 1999, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a particular high-pressure spray nozzle having a rotationally symmetrical nozzle body with a coaxial supply bore for a fluid to be sprayed. The bore tapers to an elliptical opening which forms the entrance opening for an outlet channel, and the outlet channel terminates in an elliptical outlet opening with a larger cross section located in a flat outlet surface of the nozzle body.
A high-pressure spray nozzle for de-scaling or cleaning rolled metal is known from European publication EP 0 792 692 A1. An outlet channel located downstream from the supply bore expands from its entrance opening to the outlet opening by way of concave walls all the way around with curvatures which must be designed so that the wall in the outlet area does not come in contact with the high-pressure flat stream formed by the spray medium. As a result of this design, in contrast with flat stream nozzles of a different design produced by chip removal to mill a groove in the vicinity of the mouth of the supply bore (see Germany publication DE 34 14 880 A1), no sharp edges that lead to premature wear of the nozzle as a result of the fluid stream emerging under very high pressure are formed in the outlet area of the stream. This is also achieved by having the walls of the outlet channel expand xe2x80x9ctrumpetwisexe2x80x9d toward the mouth or otherwise so that they do not come in contact with the fluid stream in the vicinity of the mouth. One disadvantage of such spray nozzles is that, as a result of the lack of guidance of the high-pressure stream, the flat stream can expand, without guidance, toward the minor semiaxis of the elliptical outlet opening so that the stream pressure that can be produced is reduced.
A high-pressure cleaning nozzle is known from European publication EP 0 862 950 A1 in which a tapered pressure medium supply channel that makes a transition in the form of a hemisphere to an outlet opening is provided. At the outlet end of this high-pressure nozzle, a groove with a circular cross section that runs perpendicularly to the axis of the supply channel and extends transversely over the entire end surface is provided. In the middle of this groove, a depression with an oval shape, with parallel side walls, and with a circular bottom are also provided. This depression cuts the spherical end portion of the supply channel, thus forming a likewise oval outlet opening with edges connecting the parallel side walls which make a stepwise transition to the area of the circular bottom of the depression and then again merge stepwise with the area of the groove passing over the end. Such nozzles do not provide an opening that expands exclusively elliptically and continuously outward. The shape of the stream therefore differs from that of the high-pressure spray nozzle mentioned above. Sharp edges remain that likewise can result in premature wear.
One object of the invention is to design a high-pressure spray nozzle of the type recited at the outset such that wear by the formation of acute angles at the outlet edge is avoided but such that improved bundling of the flat stream takes place at the outlet so that the stream pressure can be increased. To achieve this object, provision is made in a high-pressure spray nozzle of the type recited at the outset that only the areas of the side walls of the outlet channel that abut the major semiaxis of the elliptical outlet opening are expanded in the flow direction while the areas of the outlet channel that abut the minor semiaxis form side walls that run essentially coaxially to the supply bore.
By this measure, the flat stream is prevented from also expanding in the direction of the minor semiaxis in such fashion that it cannot be influenced. The impact area of the flat stream can be sharply delimited so that the stream pressure is also greater than in known high-pressure spray nozzles. The advantage that no acute angles appear on the outlet edge, as is the case in spray nozzles made by chip removal, is retained.
Preferably, the side walls of the outlet channel that abut the major semiaxis are made so that they run essentially parallel to the desired boundary surfaces of the expanding fluid stream. The walls of the outlet channel that lie on the lengthwise extension of the flat stream cross section, therefore, remain as guide surfaces for the latter in contact with the flat stream.
Another feature is that the side walls of the outlet channel that abut the major semiaxis can be partial surfaces of a conical jacket. These side walls then delimit the latter in the lengthwise direction of the flat stream so that the entire high-pressure flat stream, in its entire outer area, is guided as it leaves the nozzle and can thus be kept within limits in the desired fashion. The stream pressure that can be achieved as a result is higher than according to the prior art. Therefore, if such nozzles are used for descaling or for cleaning, their cleaning action is greater.
An embodiment of the invention is shown schematically in the drawings and is described in the following.